linux-kernel - Re: [PATCH v2] xen: HVM X2APIC support

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Message-Id: <201012071004.22291.sheng@linux.intel.com>
Date:	Tue, 7 Dec 2010 10:04:22 +0800
From:	Sheng Yang <sheng@...ux.intel.com>
To:	Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>
Cc:	Jeremy Fitzhardinge <jeremy@...p.org>,
	Stefano Stabellini <stefano.stabellini@...citrix.com>,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2] xen: HVM X2APIC support

On Tuesday 07 December 2010 04:40:54 Konrad Rzeszutek Wilk wrote:
> > +static inline uint32_t xen_cpuid_base(void)
> > +{
> > +	uint32_t base, eax, ebx, ecx, edx;
> > +	char signature[13];
> > +
> > +	for (base = 0x40000000; base < 0x40010000; base += 0x100) {
> > +		cpuid(base, &eax, &ebx, &ecx, &edx);
> > +		*(uint32_t *)(signature + 0) = ebx;
> > +		*(uint32_t *)(signature + 4) = ecx;
> > +		*(uint32_t *)(signature + 8) = edx;
> > +		signature[12] = 0;
> > +
> > +		if (!strcmp("XenVMMXenVMM", signature) && ((eax - base) >= 2))
> > +			return base;
> > +	}
> > +
> > +	return 0;
> > +}
> > +
> > +#ifdef CONFIG_XEN
> > +extern bool xen_hvm_need_lapic(void);
> > +
> > +static inline bool xen_para_available(void)
> > +{
> > +	return xen_hvm_need_lapic();
> > +}
> > +#else
> > +static inline bool xen_para_available(void)
> > +{
> > +	return (xen_cpuid_base() != 0);
> 
> Would it make sense to collapse the kvm_para_available and
> the xen_cpuid_base together (and maybe even the HyperV detection code)
> together in one and just return "x2_apic_para_capable" ?

Well, no hyper-v now. But put them together is a good idea.

--
regards
Yang, Sheng
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